Froth flotation method with counter-current separation



Sept. 5, 1967 P. BOUTIN ETAL 3,339,730

FROTH FLOTATION METHOD WITH COUNTER-CURRENT SEPARATION- Filed June l9,1963 4 Sheets-Sheet 1 fierke 6o 5% I J, 7Ze777b/a.

,MW/M A924,? 71% mwi P 967 P. sou-rm ETAL 3,339,730

FROTH FLOTATION METHOD WITH COUNTER-CURRENT SEPARATION Filed June 19,1965 4 Sheets-Sheet 2 1 7 Va 9 722 is P/Zgrre 5OM7777 6277) TVeMb/QjAFT/Or 4 9 Sept. 5, 1967 P. VBOUTIN ETAL FROTH FLOTATION METHOD WITHCOUNTER-CURRENT SEPARATION 4 Sheets-Sheet 3 Filed June 19, 1963 P/erha50 a7??? fem/ fi Zeb-H4 7 m M 771% 2 Sep 1967 P. BOUTIN ETAL FROTHPLOTATIONYMETHOD WITH COUNTER-CURRENT SEPARATION 4 SheetsSheet 4 FiledJune 19, 1963 United States Patent 3,339,730 FROTH FLOTATION METHOD WITHCOUNTER-CURRENT SEPARATION Pierre Boutin, Ottawa, Ontario, and Remi J.Tremblay,

Atikokan, Ontario, Canada, assignors to Column Flotation Co. of Canada,Ltd., Ottawa, Ontario, Canada, a company of Canada Filed June 19, 1 963,Ser. No. 288,931 Claims priority, application Canada, July 14, 1962,853,771; June 4, 1963, 877,145 13 Claims. (Cl. 209-166) The presentapplication is a continuation-in-part of application Ser. No. 217,130,now abandoned, filed Aug. 15, 1962.

This invention relates to a method for the separation and recovery ofone constituent from another constituent in a comminuted mixture of suchconstituents. More particularly, it relates to a method and apparatusfor the separation and recovery of values from comminuted ores, and moreparticularly by a flotation technique.

It is now well-known that a large number of values in ores may beseparated from the gangue etc. by a flotation technique. Theseconventional separation procedures have suffered numerous disadvantagesincluding low efficiency, the need for a bank of units to carry outconsecutive batch operations and considerable maintenance requirements.

An object of the present invention is the provision of a continuousmethod for the counter-current separation and recovery of oneconstituent from a comminuted mixture containing such constituent andother constituents in a vertically upright restricted zone.

Another object of this invention is the provision of a continuous methodfor the countercurrent separation and recovery of values from acomminuted ore in a vertically upright restricted zone, wherein thevalues are flotated-ofl from an upper region of said zone, the gangueand residue is recovered from a lower region of said zone and whereinthe ore being separated is fed to an intermediate region of said zone.

Yet another object of this invention is the provision of a continuousmethod for the counter-current separation and recovery of values from acomminuted ore for a vertically upright zone wherein the gangue andresidue are flotated-oif from an upper region of said zone, the valuesare recovered from a lower region of said zone and wherein the ore beingseparated is fed to an intermediate region of said zone.

A further object of this invention is the provision of an improvedmethod for the froth flotation separation of values from gangue in acomminuted ore wherein there is enhanced recovery coupled with enhancedgrade.

The term recovery as used herein is intended to mean the ratio of solidmaterial recovered to the solid material in the feed.

The term grade is intended to mean the ratio of the desired material inthe material recovered to the total material recovered.

The present invention is operative in the froth flotation of any orewhich has successfully been separated into value and gangue by frothflotation in the past. Non-limiting examples of suitable ores include:

(1) sulphides, for example cinnabar, cobal-tite, smaltite, erythrite,chalcocite, covellite, chalcopyrite, bornite, galena, pyrite, marcasite,pyrrhotite, arsenopyrite, linneite, molybdenite, realgar, argentite andsphalterite;

(2) native metals, for example, gold, silver, copper and bismuth;

(3) oxides, for example, bauxite, cassiterite, chromite, cuprite,ilmenite, hematite, specularite, manganosite, molybdite, rutile,alunite, anglesite and cerrisite;

"ice

and

(6) inert minerals, for example coal and graphite.

These above, and other ores may be flotated according to the presentinvention through the use of the conventional regulators, depressants,activators, principal promoters, frothers, promoter-assisting agents andselectivityassisting agents well-known to those skilled in the art andselected for each of the desired ore. Conventional promoters orcollectors, those reagents which provide ores to be floated with a waterrepellant surface that will adhere to air bubbles, include anionicagents, for example the xanthates, the dithiosphosphates and the fattyacids and the cationic agents such as the fatty amine acetates.Nonlimiting examples of such conventional promotors include:

(1) anionic agents, for example, xanthates for example,

lauryl or octyl xanthates or a xanthate and Pb-thallium group reactionproduct, thiophosphates, mercaptans, thioalcohols, thiocarbanilides,mercapto-benzothiazoles and organic sulphides, for example dixanthogensand thiuram disulphides;

(2) carboxylic agents, for example fatty acids, for example aleric acid,tall oil, tall oil soap, naphthenic acid, black liquor soaps andcottonseed oil foots;

(3) sulphoxy agents for example, T urkey-red oil, and higher alcoholsulphates, for example cetyl sulphate;

(4) cationic agents, for example, amines, alkylalamines,ot-naphthylamines, onium salts, isoureas and aldoximes;

and

(5) fuel oil and kerosene.

- bracho, dichromate, Palcaton, Palconate, lime, bismuthnitrate, tannin,barium chloride, alum, bleaching powder, citric acid, gelatin, dextrine,and glue. Non-limiting examples of suitable activators include bariumsalts, lead salts, for example barium chloride and lead nitrate,phosphomolybdic acid, phosphotungstic acid, barium sulphide,

. copper sulphate, hydrogen fluoride, sodium sulphide, and

ferric chloride.

Non-limiting examples of suitable frothers include cresylic acid, pineoil, aniline, xylidine, pyridine and eucalyptus oil. Non-limitingexamples of suitable pro moter-assisting agents include kerosene, fueloil, aniline, pyridene, orthotoluidine, various detergents, pine taroil, higher alcohol sulphates and creosotes. Non-limiting examples ofsuitable selectivity assisting agents include sodium silicate, citricacid, hydrogen fluoride, starch, dextrine, quebracho, gum arabic,polyphosphates, sulphuric acid, fluosilicates, dichromates, Palcaton,Palconate, various acids, alum, alkali resinates, sodium fluoride,caustic starch and guar gum.

It will, of course, be appreciated that the particular regulator,depressant activator, promoters, frothers, promotor-assisting agents andselectivity-assisting agent is selected according to the particular orebeing treated. Thus, for example, to recover the mineral barite from anore, a recommended regulator is either sodium carbonate or sodiumsilicate, a recommended depressant is either ferric chloride or aluminumchloride, a recommended activator is either a barium salt or a leadsalt, a recommended promoter is oleic acid or a higher alcohol sulphate,a recommended frother is pine oil or cresylic acid, a recommendedpromoter-assisting agent is N-octadecyl disodium sulphosuccinate and arecommended selectivity-assisting agent is either sodium silicate orcitric acid.

The proportions of the various ingredients added to the ore is withinthe range well-known to those skilled in the froth-flotation art. Thus,the usual amount of promoters used is within the range of 0.010.2lb./ton for the aryl dithiophosphoric acid type; 0.05-O.2 .lb./ton forthe xanthate type; 0.050.5 lb./ ton for the thiocarbanilide type; 0.22.0lb./ton for the fatty acid-type of vegetable origin; 0.10.5 lb./ton forthe amine or amine salt type; 0.5-3.0 l b./ton for the anionicsulphonate-type; 0.22.0 lb./ton for the fatty acid or fatty acid soapstype; and 0.54.0 lb./ ton for the kerosene or hydrocarbon type.

With respect to the various flotation modifying agents, the followingproportions may be used:

(1) Alkalies: lime, 0.55.0 lb./ton; soda ash or alkaline silicates,0.5-3.0 lb./ton; sodium hydroxide, 0.54.0

lb./ton; and alkaline phosphates, 0.52.0 lb./ton;

(2) Acids: sulphuric, 0.5-5.0 lb./ton; hydrofluoric and phosphoric,0.54.0 lb./ton; and citric and tactic, 0.52.0 lb./ton;

(3) Cyanogen compounds: alkaline cyanides, 0.010.5 lb./ton; andferrocyanides and ferricyanides, 0.12.0 lb./ton;

(4) Sulphites and sulphides: alkaline sulphites, 0.5-4.0 lb./ton;sulphur dioxide, 1.010.0 lb./ton; hydrogen sulphide, 0.2-2.0 lb./ton;alkaline sulphides, 0.55.0 lb./ton; and alkaline oxychlorides, 0.5-2.0lb./ton;

(5) Salts of metal ions; copper sulphate, chromic acid and dichromates,0.25.0 lb./ton; mercuric nitrate, lead nitrate, lead acetate, aluminumsulphate, aluminum chloride, manganates and permanganates; 0.1-2.0 lb./ton; and ferrous sulphate and ferric sulphate 0.l-1.0 lb./ton; and

(6) Organic colloids; quebracho, tannic acid, Palcoton and Palconate,and glue, 0.l0.5 lb./ton; synthetic organic depressants, 0.1-1.0lb./ton; and starch, 0.11.0 lb./ton.

In the case of frothers, in conventional practice they are used toenhance and assist in the introduction of small air bubbles into theflotation pulp and the collection of the unbroken mineral-laden bubbleson the pulp surface. For this purpose frothers such as the synthetichigher alcohol type have heretofore been used in amounts of from0.01-0.5 lb./ton; pine oil has been used in an amount of 0.03-0.2lb./ton; while cresylic acid and eucalyptus oil have been used in anamount of 0.050.2 lb./ton. However, in the present invention, thefrother is used to control the air bubble size. To achieve this end, theamount of frother which may be used is generally less than that usedheretofore. The bubble size is controlled in this manner preferably toachieve optimum surface are of the bubbles per volume of the column.

The rate of introduction of aqueous washing medium at the top of thevertically erect column, the rate of introduction of air at the bottomof the vertically erect column and the rate of introduction of feedslurry at a point between the top and the bottom of the vertically erectcolumn are all interdependent.

Stated in its broadest terms, however, the column should be operated atits optimum capacity for a given ore while retaining a maximum recovery,but at conditions which do not approach flooding conditions. By floodingconditions is meant that the downward velocity of the material in thecolumn is such that it decreases the velocity of the rising bubbles tosuch an extent that more bubbles are produced than can escape from thetop 4 of the column. This results in a compacted bubble condition whichleads to a violent swirling action and explosive ebullition within thecolumn, which severely hinders and may sometimes completely interferewith the separation.

Stated another way, moreover, the air pressure, which controls the rateof introduction of air at the bottom of the column, must be greater thanthe hydrostatic pressure on the means which provides the air bubblesi.e. the bubbles or diffuser. This expression may be expressedmathematically, as follows:

p==hd+k where p is the pressure of air delivered to the bubbler ordiffuser, h is the height of the column, d is the average density of thecontents of the column and k is a factor (which is greater than 0 butless than 7) which is a characteristic of the bubbler or diffuser Apressure of air of up to about 20 p.s.i.g. is usually used.

It is clear from the above formula and description that the amount ofair passing through the column per unit time per unit area ofcross-section of the column is a function of the slurry flow rate andthe density of the slurry, the number of air bubbles, and the size ofthe air bubbles. The means to form the bubble of air may be any suitableperforated member. One type which has been found suitable is a conicallyshaped porous metal air diffuser, generally having perforations of asize 5 microns to 2500 microns with a size of 10 microns beingparticularly preferred. With perforations within this range, the bubblesize would normally range from about 1000 to about 10,000 microns with apreferred size being about 1600 microns. Of course, as specified above,the frother is used to control the bubble size and so the bubble sizecan be maintained at a reasonable size even with larger perforations inthe perforated member. A size of between 3000 microns and 6000 micronsis permissible although other sizes are possible. Another type which hasbeen found suitable is a cylinder having an ellipsoidal icross-section,whose closed ellipsoidal end is of porous metal having perforations ofthe sizes referred to hereinabove. Additionally porous metal plateshaving apertures of the sizes referred to hereinabove, porous ceramicplates having apertures of the sizes referred to hereinabove and othermeans such as punctured rubber, filter cloth, etc., with apertures ofthe sizes referred to hereinabove are suitable. Such means must beconnected to a source of air under pressure which is separated from theinterior of the column except through such porous means. 7

As in conventional practice, the ore is crushed, screened, ground andclassified and formed into an aqueous slurry. In the present invention,however, the slurry is formed in an agitation conditioning tank, whichcontains means for intimately mixing the ground ore with the water andwith the necessary conditioning and flotation agents. The slurry usuallycontains from about 5 to about solids, but this is dependent upon theparticular ore being slurried. The slurry from the agitationconditioning tank must be in pumpable form and is fed at such a ratethat the slurry entering the column as feed contains more solids thanare in the column at any particular instant of time. This may requirechanges in the flow rate and/or solids conhereinabove, dependent uponthe various parameters of the system. Generally speaking the rate offlow is such that it dilutes the slurry to prevent the unseparatedslurry from rising.

By one broad aspect of this invention, there is provided a method forthe separation of one constituent from another constituent in acomminuted mixture of those constituents, the method comprising,firstly, establishing and maintaining a downwardly flowing stream ofaqueous medium within a vertically aligned, elongated zone, said aqueousmedium being introduced at an upper portion of said zone; thenestablishing and maintaining an upwardly moving stream of air bubblesoriginating at a lower portion of that zone wherein the downwardvelocity of said aqueous medium is not greater than the upward velocityof said stream of air bubbles; then establishing an aqueous slurry ofthat comminuted mixture and at least one conditioning agent whichrenders one of the constituents hydrophobic; then introducing thatslurry into that zone at a region in the zone above the lower portionbut below said upper portion at such a rate that the solids content ofthe slurry is greater than the solids content in said zone; thenwithdrawing one constituent and air as overflow at the upper region ofsaid zone, said one constituent and said air moving co-currently to saidupper portion; and finally withdrawing the other constituent and wateras underflow at the lower region of said zone, said other constituentand said aqueous medium moving co-currently to said lower portion.

This method may be used to collect the values in the ore in the form ofsolid particles adhered to the air bubbles, with the gangue beingcarried out as underflow from the bottom of the column, oralternatively, may be used to collect the gangue in the form of solidparticles adhered to the air bubbles and to collect and recover thevalues as underflow. Advantageously, the method is conducted bycorrelating the rate of input of water with the rate of input of slurryfeed and the rate of underflow to maintain a substantially constantupper level in the column. Also, the air bubbles may be produced bypassing the air under pressure through a perforated member, the pressurebeing up to about p.s.i.g., the size of perforations being about 5 toabout 2500 microns, with the air bubbles having a size of about 1000 toabout 10,000 microns. The slurry usually has a solids content of about5-75%. The process is particularly suited for the separation of quartzas overflow from iron values as underflow, the separation of quartz anddolomite as overflow from iron values as underflow, dolomite and ironvalues as overflow from quartz as underflow, of molybdenum sulphide andbismuths as overflow from gangue as underflow, of molybdenum sulphide asoverflow from gangue as underflow and copper values as overflow fromgangue as underflow.

The apparatus used in carrying out the method of this inventionpreferably includes an upper zone, an intermediate zone and a lowerzone. The water inlet means usually extends into the upper portion ofthe upper zone. The slurry feed inlet is to the intermediate zone. Thebubbler is situated in the lower zone and at the lower portion of thelower zone there is provided outlet means for the underflow. Collectingmeans are provided at the upper portion of the upper zone. Preferably,means are included for the preparation of the feed slurry. A preferredfeature of the invention is the reduction of the cross-sectional area ofthe upper zone by about A to of the area of the other two zones, as by areduction in its diameter or by insertion of an axial solid tube thereinor an axial slurry feed line. In the latter case, the water inlet meansmay be concentric with the slurry feed line. The bubbler may be aconical member with fluted perforated walls, or an elliptical cylinder,the top of which is perforated, these vessels being connected to asource of air under pressure. In each case the perforations may be about5 to about 2500 microns in size. In another embodiment the uppercollecting means includes a top chamber to an inclined weir therein andan inclined outlet cooperating with the weir.

In the drawings,

FIG. 1 is a schematic view partly broken away, of one embodiment ofapparatus according to this invention,

FIG. 2 is a vertical cross-section of the flotation column of FIG. 1,

FIG. 3 is a section along the line IIIIII of FIG. 2,

FIG. 4 is a section along the line IV-IV of FIG. 2,

FIG. 5 is a vertical cross-section of a top portion of a flotationcolumn according to another aspect of this invention,

FIG. 6 is a vertical cross-section of a top portion of a flotationcolumn according to another aspect of this invention,

FIG. 7 is a vertical cross-section of a top portion of a flotationcolumn according to yet another aspect of this invention,

FIG. 8 is a vertical cross-section of a top portion of a flotationcolumn according to still another aspect of this invention,

FIG. 9 is a vertical cross-section of a bottom portion of a flotationcolumn according to a further aspect of this invention, and

FIG. 10 is a section along the line X-X of FIG. 9.

Turning first to FIG. 1, the flotation column indicated generally at 10comprises an upper section 11, an intern1ediate section 12 and a lowersection 13. The cross-section of the flotation column may be circular,elliptical, square, rectangular or any other transverse section of aplan geometrical figure. As shown in FIGS. l-4, the cross-section of thecolumn is circular. In addition the length of the column should begreater than the width thereof, and a ratio of lengthzwidth 6:1 or morehas been found to be satisfactory. It is desirable to have the insidesurfaces of the column smooth to minimize turbulence.

As shown in FIGS. l-4, the column 10 is constructed of a plurality ofsections in vertical axial alignment. Upper section 11 comprises twosections 14 and 15 which are each flanged to facilitate assembly bybolts or other means not shown in the drawings.

Intermediate section 12 is compressed of a main flanged section 16 tofacilitate assembly by bolts or other means not shown in the drawings,and an integral inlet leg 17, also provided at its open end with aflange.

The lower section 13 comprises a flanged main portion 18, a flangedinverted frusto-conical portion 19 and a flanged outlet portion 20including a cylindrical section terminating in an invertedfrusto-conical outlet 21. The frusto'conical outlet is attached to anelbow conduit 22 which conducts eflluent from the column through valve23 to outlet conduit 24.

Air under pressure in tank 25 is led by line 26 through valve 27 to adifluser or bubbler 28 disposed in portion 19, by means of elbow pipe29. As shown in FIGS. l-4, the diffuser or bubbler 28 is ofapproximately conical shape having its conical wall fluted verticallyand provided with a plurality of small orifices. Air under pressurepasses through such plurality of orifices and is delivered to the lowerportion 13 of the column.

The feed slurry is pumped into the central portion 12 through inlet leg17 by means of pump 30 from agitating conditioning tank 31. This tankhas a generally cylindrical shape, terminating in a frusto-conicalbottom 32. Within the tank is an impeller 33 fixed to a vertical shaft34 which is adapted to be rotated by means (not shown) associated with apulley 35 splined to the shaft 34. The tank is provided with a removablecover 36, to enable the ore and flotation ingredients to be added to thetank. Water, which forms the aqueous phase of the slurry, is admittedthrough inlet conduit 37.

Downwardly flowing aqueous medium is admitted to the upper portion 11 ofthe column 10 by means of valved inlet conduit 38 which terminates in afeed tube 39 extending into the upper portion 11 of the column 10.

Foam, consisting of solid particles adhered to the rising air bubblesoriginating from diffuser or bubbler 28, collects in section 14 and isdrawn-off through a downwardly disposed angularly extending dischargeconduit through open valve 23. Air is admitted,'under the re-- quiredpressure to overcome the hydrostatic pressure, through lines 26 and 29to the diffuser 28, where an upwardly directed stream of bubbles iscaused to be directed 40, at the top of section 14. through the column10. The ore, in the form of an aque- FIGS. 5-8 depict alternativeconstructions of the upper ous slurry of the desired solids content, andcontaining portion 11 of the column 10. In the embodiments shown apromoter or collector which provides the values with in FIGS. 5, 6 and 7a means is provided in the upper 31 water-repellant surface which willadhere to air bubbles, zone to reduce the cross-sectional area thereof.This is as well as any desired controlling or modifying agents for themain purpose of increasing the velocity of flow 10 and the requiredamount of frother to control air bubble of the aqueous washing medium toenhance the consize, is then pumped via pump 30 from tank 31 to inlettamination minimizing effect in the upper portion 11. In leg 17 andthence to the intermediate portion 12 of the FIG. 5, thiscross-sectional area reducing means comcolumn 10. The values, havingsuch water-repellant surprises a solid tube 41 inserted in the regionbetween the face, adhere to the air bubbles and are carried upwardlydischarge conduit 40 and the inlet leg 17. In FIG. 6, 15 to be removedat discharge conduit 40. The gangue and the cross-sectional areareducing means is provided by other extraneous material, not having suchwater-repelforming the upper portion 11 between the discharge conlantcoating are carried downwardly with the water and duit 40 and the inletleg 17 of a tube 15' of reduced are discharged, along with the water,through discharge diameter than the diameter of tube 18. In FIG. 7, theline 22 and 24. cross-sectional area reducing means is provided by a Asstated hereinbefore, if it is desired to remove the feed inlet conduit43 extending downwardly along the gangue and other residues as foam,such foam would be longitudinal axis of the column 10 to a regioncorrediscarded, if not needed, but the values carried along withsponding to the intermediate portion 12. The conduit 43 the water, willbe recovered at discharge line 24. is provided with a nozzle aperture44. In addition, the The following examples are given still further toillusaqueous washing medium is admitted through conduit 25 trate thepresent invention. 42 which is concentric with inlet tube 43.

The embodiment shown in FIG. 8 relates to a modified EXAMPLE 1 foamremoval system. In that figure there is shown an Amme fl n f quartz fromiron are enclosed box 45 having a plurality of sloping weirs 46PROCEDURE therein, leading to the discharge conduit 40. The foam isadapted to pass through the weirs 46 into zone 48 from Ten barrels ofIron ore We're rfacelved from the m which it is withdrawn throughdischarge conduit 40. The Ore compafny Canada- Thls shlpment, 60% ofWhlch aqueous Washing medium enters through radial inlet tube were of a5125 mmus 325 mesh known a Lean Blue 39 and its flow is directed by rims47 upstanding from averaged 54 to e, 15 to 17% 2 and approxl' the uppertubular section 15. mately 3% loss on lgmtlon' The embodiment of FIGS. 9and 10 is directed to a h -F F batch, approxlmately 75% sohds. wmodified diffuser or bubbler. The bnbbler or diffuser 49 condltloeedW1fl 1NaOIfI(PH11)theI{ W1th 1 1b-/ton sohds is an ellipsoidal cylinderhaving its bottom 50 of of dextrm and immediately after this addition, 1lb./ton porous material and provided an inlet conduit 51 for the sohdsof Pnmary coconut 011 l m was addedfeed air under pressure admittedthrough line 29. Its sides was Pumped mm a column slmllar to that shownIn the are also non-porous, but its elliptical cross-sectioned topdrawmgs- I 52 is provided with a plurality of 10 micron diameter ori-Half an hour after the column W Operated, tlmed fices samples ofunderflow (from conduit 24) and overflow The operation will now bedescribed with reference (frPm condult 40) were takPn Periodically,dried, to FIG. 1 for an ore in which it is desired for the valuesWelghed and analysed The denslty and flow Tale Of the to be frothflotated. Of course it is equally applicable for underflow were keptores in which it is desired for the gangue and other exone hunfhed andPmety 51X expenments Were done, traneous materials to be froth fiotated,leaving a residue each eXPETIII'IBIIt lasting at least 11/2 1 18. f 1The following results are representative experiments Aqueous washingmedium for example water, is passed carried out according to theoutlined procedure.

TABLE 1 Test Test Test Test Test Test Test 2-1 5-1 37-1 42-1 43-1 46-156-2 Feed:

Density, g./m1 2.33 2. 30 2.30 2.30 2.3 2.3 1.98 Solids, percent 74.574.5 74.5 74.5 74.5 65.0 Flowrate,ml./min 146 66 Underflow:

Density, g./mJ 1.57 1.45 1.51 1.61 1.63 1.70 1. 59 Solids, percent. 4639.5 43.5 48 49.0 52.0 47.5 Flowrate, mL/min. 205 202 800 800 800 800800 Overflow: flowrate, m1. 30 28.6 99.8 80.8 118.5 131 107 Airrate:ml./min.NTP 450 325 1,600 2, 400 2,000 1,000 1,800 ColumnCharacteristics:

Diameter, inch 1 1 2 2 2 2 2 Upper section, feet 6 6 21 21 21 14 20Lower section, feet. 3 3 6 12 12 7 7 Capacity, ton/inch day .36 29 31 3538 42 .36 Results:

Underflow- Percent Fe 63.5 65.0 62.7 65.9 64.3 64.1 62.0 Percent S10;2.1 2.0 3.4 1.4 4.0 3.5 5.8 Overflow- Percent Fe 11.3 23.5 12.7 10.011.0 12.5 8.7 Percent sioru. 82.7 64.6 80.7 83.5 77.9 81.3 86.2 PercentFe Recovery..-" 96. 7 91. 8 96. 5 98.1 96. 6 96. 5 97. 6

downwardly through the column 10 from inlet conduit 38 and 39 and outthrough discharge line 22 and 24 These results show that the procedureof the present invention may be used to separate quartz, as the frothcd9 overflow, from iron ore, as the underflow, with a percent ironrecovery of between 91.8 and 97.6.

10 23% iron oxide, 66% quartz and 11.5% dolomite. The sieve analysis wasas follows:

Mesh: Percent wt. EXAMPLE 2 +65 7.4 Flotation of quartz and dolomitefrom iron ore PROCEDURE +325 :T 18:0 Three barrels of Cyclone productswere received from -325 33. the Iron Ore Company of Canada. Thisshipment from The Slur t ry feed at approximately 70% solids was conCarOl Lake; LabYadPY, aver age127% 55% 3 i ditioned with H 80 (pH=6.3)sulphonated petroleum 9% dolomlte- The oxlde 1S mostly speculante Wlthoil and tall oil. All of the underflow and overflow were some magnetite11 1 d 'w h d 1 d d a1 sed. The results The slurry feed batch,approximately 72% solids, was iz g g f Samp e an an y conditioned withlime, corn starch, petroleum sulpho- 15 TABLE 3 nated oil and tall oil.In the following series of eXp i Feed; weight of solids 1 0 ments whenthe column reached equilibrium all of the Reagent; underflow andoverflow were collected, dried, Weigh d, 50 -1: 3 "lb/ton" 1 3 Sampledand analysed- Sulphonated petroleum do /2 Tall oil do 1 TABLE 2Underflow: Test CP-l Time hours 33 Feed: Flowrate, typical ml./min 800Density g./ml. 2. Density, typical g./-rnl 1.28 Solids percent 7 Wt. ofsolids lbs 995 Weight lb. 250 Air Rate ml./min 1050 Reagent: Overflow:wt. of solids lbs 762 Lime lb./ton 0.5 Column characteristics: Starchlb./ton 0.25 Diameter inches 2 Sulphonated petroleum lb./t0n 0.25 Uppersection feet 15 Tall oil lb./ton 0.25 Lower section do 6 Underflow:Capacity tons/inch day-.. .22

Density 1.21 Results: Flowrate -ml./min. 795 Underflow Weight lb. 29-1Percent Fe 1.6 Overflow: Percent SiO 97.1 Weight lb. 2 .1 Percentdolomite 0.8 Time 111. 2.2 Overflow. Air rate rnL/min. 650 Percent Fe35.5 Column characteristics: 40 Percent Si0 24.6 Diameter inch 2 Percentdolomite 24.7 Upper section feet 15 Percent Fe recovery 94.3 Lowersection feet 6 v The results 111 Table 3 mdrcate that dolomite and iron2 ggp ton/Inch day 0'089 values may be flotated from quartz in an ironore, using d6 rfiow the apparatus and process of the present invention,re-

Percent Fe 43A suiting in a recovery of 94.3% Fe.v Percent SiO 26.0EXAMPLE 4 Percent dolomite 1 -9 Bulk and selective flotation ofmolybdite OVeIfiOW- 4 The column and the process of the presentinvention Percent Were used to effect bulk flotation and a selectiveflotation Percent S102 7 of molybdite. The detailed operating conditionsand test Percent dolomlte results for Run No. 4, a bulk flotation andRun No. 5, Percent Fe Recovery a selective flotation are given below:The results in Table 2 indicate that quartz and dolomite Ru No. 4,-BulkFlotation (Mo and Bismuth) may be floated ofl from iron values in ironore, in a col- Lower Zone 10 ft dia umn and process of the presentinvention, resulting in a UPper zone 9 recovery of 90.4% Fe. ReagentszKerosene 1 0.1#/ton. EXAMPLE 3 Pine oil and Dowforth 250 (1:1) 0.1#/ton.Flotation of dolomite and iron ore from quartz Ai Z 6 (potassmm amylXanthate) r s.c. .m. PROCEDURE Flowrate 1356 ml./min. Five barrels offine spiral tailings were received from average. Iron Ore Company ofCanada. This shipment averaged Solids 13% average.

TABLE 4 Assay Distribution Wt. Pewrctent MoSi Bi Cu Fe 111501. MoSa BiMOSL- 0.24 0.9 47.3 9.60 0. 35 9.60 18.1 92.3 84.5 Tails 25. 30' 99.1 0.030 0.016 7.7 15.5 Feed 25.54 100.0 0. 47 0.10 100.0 100.0

pled and analysed. The results are given below. 75'

1 I 1 2 Run No. 5.Selection Flotation (Molybdite O'nly) EXPERIMENTOP-l3-1 FEED Lower zone 10 Weight of slurry "tons-.. 0.0964 Upper zone 9ft.-2" dia. Density g./ml 1.886 R ents: Solids ..percent 72.0 Kerosene1#/ Weight of solids ..tons 0.0695 Pine oil Dowfroth 250 1 1) 0.1#/ton.Factor ton/1b Sodium silicate 0.2# /ton. REAGENTS Air min. {1218c 0.681b./t0n==21.4 g. Flowrate 1360 mL/min. 10 8 Z6 0.01 lb./ton=0.3 g.Denslty Triethoxy butane 0.051b./ton=1.6 g. Solids 12%. Sodium sulphite0.231b./ton=7.3 g.

TABLE 5 Assay Distribution Wt. Pagygnt MOS: Bi Cu Fe Pb Insol. MoSa BlThe results of Runs No. 1-6 are summarized below in TEST Table 6.

TABLE 6 Time, Flowrate, Density, Air Rate;

mm. nil/min g./ml. s.c.f.h. Run No Float M0 B1 Cu Fe Insol. Recovery .3828 it: Q32 81% 2% 25:3 82:8 33 333 1g; g-g 12.10 0.38 3.15 17.0 94.4 401 000 11118 5 92.3 4 B 47.8 9. 00 0.35 9.60 18.1 28M 60 1,000 1-128 6lective- 19.4 6.56 0.26 0.71 13.9 90.0 35 9g 1, 838 Egg a -.do 9 99 so1,010 1: 121 3:5 as 1888 Hit 110 1:010 11127 315 The results of Tables4, 5 and 6 indicate that the col- L126 umn and process of the presentinvention can separate 40 M08 and Bi from molybdite ore with a grade ofabout 95% and a recovery of 94-95%. Duratlon of test 120 Averageunderflow rate 1000 mL/min. EXAMPLE 5 g Average underflow density 1.122g./min. Flotation of copper from copper are Average underflow SolidsEercent PROCEDURE Volume of underflow collected 13.0 liters. Weight ofunderflow collected 2.67 kg. Five barrels of classifier overflow wereutilized. Each Total Weight f u d fl (calculated) 245 barrel weighed 600lb. at approximately 40% solids. Total weight f v flow contacted 2 7 k5111;011:1252; were left to settle and the clear water was COLUMNCHARACTERISTICS The weight of solids used in every batch was deter-Diameter inches 2 mined by density measurement as shown in ExperimentLower zone feet 12 cp. 13 1 7 Upper zone do 7 Conditioning time withlime and R208 (the sodium neu- Cap y .ton in :h d y 0115 tralizedreaction product of diethyl and s-dibutyl phos- RESULTS phoric acids)was half and hour before adding Z6 (po- I tassium amyl xauthate andfrother). welght of q flqated=9'94% The column operation was started 5minutes after the underflow ana13fS1s=0'20% Cu addition of frother andhalf an hour was allowed for the Overflow analysls=zo-4% Cu column toreach equilibrium before sampling. Copper Recovfiry=9 All of theoverflows were collected during each ex- EXPERIMENT 01 43-2, periment.The underfiow rates and densities were deter- [FEED mined .at specificintervals by taking 1 liter sample which wa then used for the compositeunderflow sample. Weight of Slurry -0 The total weight of the underflowwas obtained using Density 1.863 two methods: e e 8 m; f-l& P mg to sois tons.. 0.0593 (A) denslty-flowrate-percent solids-time Factor ton/1b"3&8 (B) Weight sample REAGENTS samp 6 Lime 0.05 lb./ton=1.8 g. Thedensity of the underflow averaged 2.53 g./ml. Meth- R208 0.07lb./ton=2.6 g. ods A and B checked within less than 1% Z6 0.01lb./ton=0.4 g. The overflow and underflow were filtered, dried, sam-Sodium sulphite 0.231b./ton=8,4 g.

Triethoxy butane 0.09 lb./ton=3.3 g.

13 TEST Time, Flowrate, Density, Air Rate, min. mL/min. g./ml. s.c.f.h.

Duration of test 105 min. Average underflow rate 942 ml./min. Averageunderflow density 1.170 g./ml. Average underflow solids 24.2 percent.Volume of underflow collected 11.0 liters. Weight of underflow collectedNot recorded. Total weight of underflow (calculated) 28.0 kg. Totalweight of overflow collected 3.96 kg.

COLUMN CHARACTERISTICS Diameter inches 2 Lower zone feet 12 Upper zonedo 7 Capacity ton/inch day 0.155

RESULTS weight of overflow floated: 12.4% underflow analysis:0.09% Cuoverflow analysis: 16.93 Cu Copper Recovery-:96.0%

EXPERIMENT OP133 FEED Weight of slurry tons 0.149 Density g./ml 1.928Solids V percent 73.5 Weight of solids tons 0.1095 Factor g. ton/1b--49.6

v REAGENTS Lime 0.051b./ton:2.5 g. R208 0.07 lb./ton:3.5 g. Z6 0.01lb./ton:0.5 g. Triethoxy butane 0.09 lb./ton:4.5 g.

9 EST Time, Flowrate, Density, Air Rate, min. mL/min. g./n1l. s.c.f.h.

Duration of test 160 min. Average underflow rate 800 ml./min. Averageunderflow density 1.206 g./ml. Average underflow solids 28.2 percent.Volume of underflow collected Not recorded. Weight of underflowcollected 30 kg. Total weight of underflow (calculated) 43.5 kg. Totalweight of overflow collected 6.10 kg.

.OOLUMN CHARACTERISTICS Diameter in hes 2 Lower zone feet-.. 12 Upperzone do 7 Capacity .ton/inch day 0.156

14 RESULTS weight of overflow floated: 12.3% I underflow analysis:0.08%Cu overflow analysis: 18.35% Cu Copper Recovery=96.7%

EXPERIMENT OP-13-4 FEED Weight of slurry tons- 0.137 Density g./ml 1.928Solids percent 73.4 Weight of solids tons 0.104 Factor g. ton/lb 45.5

REAGENTS Lime 0.05 lb./ton:2.3 g. R208 0.07 lb./t0n:3.2 g. Z6 0.011b./ton:0.4 g. Triethoxy butane 0.08 lb./ton:3.6 g.

TEST

Time, Flowrate, Density, Air Rate, min. ml./min. g./ml. s.c.f.h.

Duration of test 150 min. Average underflow rate 1040 ml./min. Averageunderflow density 1.196 g./ml. Average underflow solids 27.3 percent.Volume of underflow collected 11.0 liters. Weight of underflow collected3.39 kg. Total Weight of underflow (calculated) 52.2 kg. Total weight ofoverflow calculated from the combined overflow of OP-13-4, OP135 andOP13-6 (see feed OP- 13-7) 7.35 kg.

COLUM'N CHARACTERISTICS Diameter inches 2 Lower zone feet 12 Upper zonedo 7 Capacity ton/inch day 0.198

RESULTS Weight of overflow floated: 12.3

underflow analysis=0.12% Cu overflow analysis (from composite feedOP-13-7):

Copper Recovery=95.7%

EXPERIMENT OP135 FEED Weight of slurry remaining from OP-134 tons 0.0375Weight of slurry do 0.1425 Density g./m1 1.923 Solids percent 73.3Weight of solids tons 0.0769 Factor g.tons/lb 34.4

REAGENTS Lime 0.05 lb./ton=1.7 g. R208 0.07 lb./ton:2.4 g. Z60.01lb./ton:0.3 g. Triethoxy butane 0.08lb./ton=2.7 g.

TEST

Time, Flowrate, Density, Air Rate, min. rnlJmin. g./m1. s.c.f.h.

Duration of test 180 min. Average underflow rate 1080 mL/min. Averageunderflow density 1.156 g./ml. Average underflow solids 22.3 percent.Volume of underflow collected 10.0 liters. Weight of underflow collected2.56 kg. Total weight of underflow (calculated) 49.8 kg. Total weight ofoverflow calculated from combined overflow OP-13-4, OP135 and OP-13-6(see feed OP137) 7.65 kg.

COLUMN CHARACTERISTICS Diameter inches 2 Lower zone feet 12 Upper zonedo 7 Capacity -tons/inch day 0.161

RESULTS Weight of overflow floated-=13.3

Underflow analysis=0.12% Cu Overflow analysis (from composite feedOP-13-7)-=18.58% Cu Copper recovery=95.9% 1

EXPERIMENT OP-13-6 FEED Weight of slurry remaining from OP-13-5 tons0.048 Weight of slurry d0.. 0.155 Density g./rnl 1.952 Solids percent76.4 Weight of solids tons 0.083 Factor g. tons/lb-.. 37.5

REAGENTS Lime 0.05 lb./ton=1.9 g. R208 0.07 lb./ton=2.6 g. Z60.01lb./ton=0.4 g. Triethoxy butane 0.08 lb./ton=3.0 g.

TEST

Time, Flowrate, Density, Air Rate,

min. ml./mir1. g./ml. s.c.f.h.

16 Duration of test 240 min. Average underflow rate 1009 mL/min. Averageunderflow density 1.174 g./ml. Average underflow solids 24.5 percent.Volume of underflow collected 17.0 liters. Weight of underflow collected4.72 kg.

Total weight of underflow (calculated) 68.8 kg. Total weight of overflowfrom combined overflow OP134, OP-13-5 and OP- Weight of overflowfloated: 13.3 Underflow ana1ysis=0.11% Cu Overflow analysis (fromcomposite feed OP-13-7) =18.58% Cu Copper recovery=96.1%

EXPERIMENT OP-13-7 FEED Weight of combined overflow slurry fromExperiments OP13-4, OP-13-5 and OP-13-6 lb 102.0

Density 'g./m1 1.693 Solids "percent" 56.2 Weight of combined overflowlb 57.3

REAGENTS Sodium sulphite 0.23 lb./ton ore=22.0 g. Triethoxy butane 0.025lb./ton feed=0.3 g.

TEST

Time, Flowrate, Density, Air Rate,

min. ml./min. g./ml. s.c.f.h.

Weight of dry overflow collected 6.23 kg. Weight of dry underflowcollected 5.33 kg. Total weight 11.56 kg.

COLUMN CHARTERISTI'CS" Diameter "inch" 1 Lower zone ..feet 12 Upper zonedo 6 Capacity -Jons/inch day 0.621

RESULTS Weight of overflow floated=53.9% Analysis of underflow=6.92% CuAnalysis of overflow=28.5% Cu The feed for Test 7 was obtained bycollecting the overflow of Tests 4, and 6. The underflow from this testwould be returned to the grinding circuit and from there it would becomepart of the feed to the rougher scavenger column.

The results summarized in Table 7 indicate that the apparatus andprocess of the present invention can be used to flotate copper valuesfrom a copper ore. The percentage Copper in the concentrate ranges from16.9-20.4, the percentage copper in the tailings ranged from 0.08 to0.20, and the recovery is from 91.8-96.7%.

We claim:

1. A froth flotation method for the separation of one constituent fromanother constituent in a comminuted mixture of said constituents whereina constituent thereof, which is at that time hydrophobic, is withdrawnas a froth with air, said method comprising:

(a) establishing and maintaining a downwardly flowing stream of aqueousmedium within a vertically aligned, elongated zone, said aqueous mediumbeing introduced at an upper portion of said zone;

(b) establishing and maintaining an upwardly moving stream of airbubbles originating at a lower portion of said zone, wherein thedownward velocity of said aqueous medium is not greater than the upwardvelocity of said stream of air bubbles;

(c) establishing an aqueous slurry of said comminuted mixture and atleast one conditioning agent which renders a selected said constituenthydrophobic;

(d) introducing said slurry into said zone at a region in said zoneabove said lower portion but below said upper portion at such a ratethat the solids content of said slurry is greater than the solidscontent in said zone;

(e) withdrawing constituent rendered hydrophobic and air as overflow atthe upper region of said zone at a point above said downwardly flowingstream, said constituent rendered hydrophobic and said air movingco-currently to said upper portion;

(f) withdrawing said other constituent and aqueous medium as underflowat the lower region of said zone at a point below the introduction ofsaid upwardly moving stream, said other constituent and said aqueousmedium moving co-currently to said lower portion.

2. A froth flotation method for the separation of the values from thegangue ina comminuted mixture of ore, wherein a constituent thereof,which is at that time hydrophobic, is withdrawn as a froth with air,said method comprising:

(a) establishing and maintaining a downwardly flowing stream of waterwithin a vertically aligned, elongated zone, said water being introducedat an upper portion of said zone, said upper portion of said zoneconstituting one-fourth of the height of said zone;

(b) establishing and maintaining an upwardly moving stream of airbubbles originating at a lower portion of said zone, wherein thedownward velocity of said water is not greater than the upward velocityof said stream of air bubbles, said lower portion of said zoneconstituting one-fourth of the height of said zone;

(c) establishing an aqueous slurry of said comminuted mixture and atleast. one conditioning agent which renders the values in said orehydrophobic;

(d) introducing said slurry into said zone at a region in said zoneabove said lower portion but below said upper portion at such a ratethat the solids content of said slurry is greater than the solidscontent in said zone; g i

(e) withdrawing said values and air as overflow at the upper region ofsaid zone at a point above the introduction of said downwardly flowingstream, said values being in the form of solid particles adhered to atthe lower region of said zone at a point below the introduction of saidupwardly moving stream, said withdrawn material having movedco-currently with said water to said lower portion, the ratio of theheight to width of said vertically elongated zone being at least 6:1.

3. A froth flotation method for the separation of the values from thegangue in a comminuted mixture of ore, wherein a constituentthereof,'which is at that time bydrophobic, is withdrawn as a froth withair, said method comprising:

(a) establishing and maintaining a downwardly flowing stream of waterwithin a vertically aligned elongated zone, said water being introducedat an upper portion of said zone, said upper portion of said zoneconstituting one-fourth of the height of said zone;

(b) establishing and maintaining an upwardly moving stream of airbubbles originating at a lower portion of said zone, wherein thedownward velocity of said water is not greater than the upward velocityof said stream of air bubbles, said lower portion of said zoneconstituting one-fourth of the height of said zone;

(c) establishing an aqueous slurry of said comminuted mixture and atleast oneconditioning agent which renders the gangue in said orehydrophobic;

(d) introducing said slurry into said zone at a region in said zoneabove said lower portion but below said upper portion at such a ratethat the solids content of said slurry is greater than the solidscontent in said zone;

(e) withdrawing said gangue and air as overflow at the upper region ofsaid zone at a point above the introduction of said downwardly flowingstream, said gangue being in the form of solid particles adhered to saidair bubbles, said withdrawn material having moved co-currently with saidair to said upper portion; and v (f) withdrawing said values and wateras underflow at the lower region of said zone at a point below theintroduction of said upwardly moving stream, said withdrawn materialhaving moved co-currently with said water to said lower portion,theratio of the height to width of said vertically elongated zone beingat least 6:1. I v

4. The method of claim 2 wherein (i) said ore is iron ore;

' (ii) said stream of air bubbles is established and maintained bypassingsair at a rate of 1050 mL/min. upwardly through a perforatedmember;

(iii) said aqueous slurry 'has a pH of 6.3 and includes said iron ore,about 590 -gms./ ton solids of sulphuric acid, about 227 gins/ton solidsof sulphonated petroleum and 1 lb./ton solids of tall oil, said slurryhaving a solids content of about 70%;

(iv) dolomite and iron values are withdrawn as overflow; and

(v) quartz is withdrawn as underflow.

5. The method of claim 2 wherein (i) said ore is molybdite ore;

(ii) said stream of air bubbles is established and maintained by passingair at a rate of 4.0 s.c.f.m. upwardly through a perforated member;

(iii) said aqueous slurry includes said molybdite ore, 45 gms./tonsolids of kerosene, 23 gms./ton solids of pine oil, 23 gms./ton solidsof Dowfroth, and 45 gms./ton potassium amyl xanthate, said slurry havinga solids content of about 13%;

(iv) said slurry is introduced at a flow rate of 1360 mL/min. such thatthe solids content of said slurry is greater than the solids content insaid' zone;

(v) molybdenum sulphide and bismuth are withdrawn as overflow; and

(vi) gangue is withdrawn as underflow.

6. The method of claim 2 wherein (i) said ore is molyb-denite ore;

1 9 (ii) said stream of air bubbles is established and maintained bypassing air at a rate of 4.0 s.c.f.rn. upwardly through a perforatedmember; (iii) said aqueous slurry includes said ore and 45 gms./

wherein p is the pressure h is the height of the zone d is the averagedensity of the contents within said zone ton solids of kerosene, 23gms./ton solids of pine and oil, 23 gms./ton solids of Dowfroth 250, and0.2 k is a factor which is greater than Obut less than 7. lb./ton solidsof sodium silicate, said slurry having a 11. The method of claim 3wherein the upwardly movsolids content of about 12%; ing stream of airbubbles is produced by passing air (iv) said slurry is introduced at arate of 1360 m1./min. through a perforated member, the pressure of airbeing such that the solids content of said slurry is greater defined bythe formula than the solids content in said zone; p=hd +k (v) molybdenumsulphide is withdrawn as overflow; wherein and p is the pressure (vi)gangue is withdrawn as underflow. h is the height of the zone 7. Themethod of claim 2 wherein 1 dis the average density of the contentswithin said zone (i) said ore is copper ore; and

(ii) said stream of air bubbles is established and maink is a factorwhich is greater than 0 but less than 7.

tained by passing air at a rate of 4.5-5.0 s.c.f.m. up- 12. The methodof claim 3 wherein wardly through a perforated member; (i) said ore isiron ore;

(iii) said aqueous slurry includes said ore and 23-309 (ii) said streamof air bubbles is established and maingms./ton solids of lime, 317gIIlS./|IOI1 solids of the tained by passing air at a rate of 325-2400ml./min. sodium neutralized reaction product of diethyl and sthrough aperforated member; 'dibutyl phosphoric acids, 4.5 gms./ton solids of po-(iii) said aqueous slurry has a pH of 11 and includes tassium amylxanthate and 23-41 gms./ton solids said iron ore, 1 lb./ton of solids ofdextrin and 1 1b./ of triethoxy butane, said slurry having a solids con-5 ton solids content of primary coconut oil amine, said tent of about 56to about 76%; slurry having a solids content of about 65-75%;

(iv) said slurry is introduced at a rate of about 650 (iv) said slurryis introduced at a flow rate of 66-146 to about 1080 ml./min., such thatthe solids conml./min. such that the solids content of said slurry tentof said slurry is greater than the solids content in is greater than thesolids content in said zone; said zone; (v) quartz is withdrawn asoverflow; and

(v) copper values are withdrawn as overflow; and (vi) iron values arewithdrawn as underflow.

(vi) gangue is withdrawn as underflow. 13. The method of claim 3 wherein8. The method of claim 2 wherein (i) said ore is iron ore;

(i) said ore is copper ore; (ii) said stream of air bubbles isestablished and main- (ii) said stream of air bubbles is established andmaintained by passing air at a rate of 650 mL/min. up-

tained by passing air at a rate of 3.5-4.0 s.c.f.m. upwardly through aperforated member; wardly through a perforated member; (iii) saidaqueous slurry includes said iron ore, 227

(iii) said aqueous slurry includes said ore and 23-309 gms./ton solidsof lime, 114 gms./ton solids of starch, gms./ton solids of lime, 317gms./ton solids of the 114 gms/ton solids of sulphonated petroleum andsodium neutralized reaction product of diethyl and s- 4.0 114 gms./tonsolids of tall oil, said slurry having dibutyl phosphoric acids, 4.5gms./ton solids of poa solids content of about 72%; tassium amylxanthate and 23-41 gms./ton solids of (iv) quartz is withdrawn asoverflow; and triethoxy butane and 104 gms./ton solids of sodium (v)iron values are withdrawn as underflow. sulphite, said slurry having asolids content of about 56 to about 76% solids; 5 References Cited (iv)said sllurry is.introduced at alrgte of about 920- UNITED STATES PATENTS1080 m ./min. such that the soi s content of said slurryis greater thanthe solids content in said zone; 4173 1/1918 Terry 209-168 X (v) coppervalues are withdrawn as overflow; and 2/1921 TOY/n6 20i9 17 (vi) gangueis withdrawn as underflow. 1869241 7/1932 Elle 2O9168 X 9. The method ofclaim 2 wherein 2047989 7/1936 WP 210-44 X 2,088,497 7/1937 Tumstra23-270.5 X

(1) said ore is copper ore, 2 25 4 (ii) said stream of air bubbles isestablished and main- 3 10/1941 Daman 209165 tained by passing air at arate of 0.35 s.c.f.m. up- 2330875 10/1943 Ems 209 166 X wardly through aperforated member; 2,423,022 6/1947 Herkenhoif 209-166 (iii) saidaqueous slurry includes said ore and 104 gms./ 2561351 7/1951 Van Aardt2'09166 ton solids of sodium sulphite and 11 gms./t0n solids 281125510/1957 Npkes 209-467 of triethoxy butane, said slurry having a solidscon- 7/1959 Bleber 209-166 X tent of about 56%; 3,037,627 6/ 1962 Hazen209166 (iv) said slurry is introduced at a rate of about 2.10 60 FOREIGNPATENTS to about 230 tmL/min. such'that the solids content of saidslurry is greater than the solids content in said gigg e zone;

(v) copper values are withdrawn as overflow; and OTHER REFERENCES (V1)gangue is withdrawn as underflow- Taggart, Handbook of Mineral Dressing,Wiley & Sons,

10. The method of claim 2 wherein the upwardly moving stream of airbubbles is produced by passing air through a perforated member, thepressure of air being defined by the formula 1945 (12-40 through 12-47).

BARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner. p=hd+k

1. A FROTH FLOTATION METHOD FOR THE SEPARATION OF ONE CONSTITUENT FROMANOTHER CONSTITUENT IN A COMMINUTED MIXTURE OF SAID CONSTITUENTS WHEREINA CONSTITUENT THEREOF, WHICH IS AT THAT TIME HYDROPHOBIC, IS WITHDRAWNAS A FROTH WITH AIR, SAID METHOD COMPRISING: (A) ESTABLISHING ANDMAINTAINING A DOWNWARDLY FLOWING STREAM OF AQUEOUS MEDIUM WITHIN AVERTICALLY ALIGNED, ELONGATED ZONE, SAID AQUEOUS MEDIUM BEING INTRODUCEDAT AN UPPER PORTION OF SAID ZONE; (B) ESTABLISHING AND MAINTAINING ANUPWARDLY MOVING STREAM OF AIR BUBBLES ORINATING AT A LOWER PORTION OFSAID ZONE, WHEREIN THE DOWNWARD VELOCITY OF SAID AQUEOUS MEDIUM IS NOTGREATER THAN THE UPWARD VELOCITY OF SAID STREAM OF AIR BUBBLES; (C)ESTABLISHING AN AQUEOUS SLURRY OF SAID COMMINUTED MIXTURE AND AT LEASTONE CONDITIONINGAGENT WHICH RENDERS A SELECTED SAID CONSTITUENTHYDROPHOBIC; (D) INTRODUCING SAID SLURRYINTO SAID ZONE AT A REGION INSAID ZONE ABOVE SAID LOWER PORTION BUT BELOW SAID UPPER PORTION AT SUCHA RATE THAT THE SOLIDS CONTENT OF SAID SLURRY IS GREATER THAN THE SOLIDSCONTENT IN SAID ZONE;